Not specifically photo related but...Remember that you’re also interviewing her to make sure it’s a good fit for you! In all job interviews, it’s important not to just sell yourself but to get the info that you need to make your decision whether taking the job will satisfy your requirements.
In addition to pay, I would think you’d want to know if you will be able to use your images in your portfolio? Do you need to credit her or mention you were 2nd shooter when you do? Will you edit yourself or turn in your sd cards? Which shots will you be responsible for? If she blogs or uses your photos for social media, will she credit you? If she can’t make it to a shoot, will you become primary or does she have a backup? If you become primary, how will that affect your pay?